Headless server

And change zeppelin.server.addr to be either the IP address or the domain name of this server. This is to allow outside connections.

Proxy

Zeppelin seems to need npm from node.js, which in turn needs to know your proxy settings. To get around this, install node.js yourself (instead of relying on what is built in to Zeppelin) and execute npm config to set its proxy settings. Below includes the instructions for installing node.js onto RedHat-type Linux distributions (CentOS, Oracle Linux, etc.). See nodejs.org for other OS's.